iMac intermittently working

[Tclare]

Hi there,

The machine in question is a 24inch mid-2009 iMac running Snow Leopard which I believe is 2.66Ghz with 4gb of RAM, however I cannot confirm the total accuracy of this as I am unable to launch the machine. The problem started around 1 week ago after a series of thunderstorms which led to numerous power-cuts. I do not have surge protectors. The machine will often work without issue for a few hours but will after time become noticeably slower with regular spinning wheels and freezing sessions. This will lead up to a point where the machine has to be restarted as it is unusable. The machine will then refuse to restart. After pressing the power button the fans will come on and a grey screen will appear. This process can be repeated several times with identical results. However, randomly the machine will proceed to work and launch into the OS.

This machine used to be my main computer and at the beginning of the weekend had only 5% of HD space remaining. Since this time I have bought a new machine. I have done a complete clean install on the old machine removing everything and reinstalling Leopard and then Snow Leopard. During this process the installer did not flag any issues with the HD and there are no noticeable noises to suggest it is a problem with the HD. I have also reseted PRAM. Currently the machine is running the latest updates to Snow Leopard.

Basically my question is what is causing the machine to do this? Is it something which I can fix myself as the machine is out of warrenty? Or do I need to take it to an Apple Store?

Thanks for your time,

 

[Detrius]

So you did a wipe and reload. Do you still have problems? It's not clear from what you've said.

 

[VulchR]

I suppose it goes without saying it might be a good idea to get a surge suppressor for your new machine.

I am no expert, but it sounds like something might be getting overheated as the machine is used. It might be worth getting a utility that displays the internal temperature of your iMac (e.g., smcFanControl). I suppose if this were a problem then (1) if waited for awhile for the machine to cool down, it should reboot more reliably and (2) it should stay on longer before crashing.

In any case sorry to hear you having problems with you machine. Good luck in fixing it.

 

[iMouse]

Hard drive, dude. Same problem I had with my Mid-2007 iMac. Freezes, beach balls, etc after about an hour of use. I was able to pull the drive out and replace it with a Caviar Black 1TB.

I wrapped the old drive in a towel and placed ice packs around it while I imaged the data. The drive is in pre-failure and keeping it cool allows it to operate for slightly longer periods of time.

The data was migrated using one of those SATA to USB adapters.

 

[FrankHahn]

Hard drive, dude. Same problem I had with my Mid-2007 iMac. Freezes, beach balls, etc after about an hour of use. I was able to pull the drive out and replace it with a Caviar Black 1TB.

I wrapped the old drive in a towel and placed ice packs around it while I imaged the data. The drive is in pre-failure and keeping it cool allows it to operate for slightly longer periods of time.

The data was migrated using one of those SATA to USB adapters.

Yes, it appears to be a hard disk problem. The hard disk may completely fail in any time. If still possible, back up the useful data. To pinpoint the problem, an extended test using the Apple Hardware Test is necessary.

 

[iMouse]

Yes, it appears to be a hard disk problem. The hard disk may completely fail in any time. If still possible, back up the useful data. To pinpoint the problem, an extended test using the Apple Hardware Test is necessary.

AHT is garbage...it has never detected anything that wasn't already obvious.

I actually had DiskWarrior detect a failing motor in a drive where AHT said all tests passed. Out of the hundreds of drives I've replaced, I think I've seen one drive where S.M.A.R.T did its job and reported a reading out of recommended spec. Another useless diagnostic.

I cringe when I see Seagate Momentus, Hitachi Travelstar/Deskstar or Samsung Spinpoint 2.5" drives.

 

[Detrius]

AHT is garbage...it has never detected anything that wasn't already obvious.

I actually had DiskWarrior detect a failing motor in a drive where AHT said all tests passed. Out of the hundreds of drives I've replaced, I think I've seen one drive where S.M.A.R.T did its job and reported a reading out of recommended spec. Another useless diagnostic.

I cringe when I see Seagate Momentus, Hitachi Travelstar/Deskstar or Samsung Spinpoint 2.5" drives.

Ditto on AHT being garbage. We almost never even run the extended utilities Apple gives authorized service providers. They are good for checking that temperature sensors are connected.

SMART, though, is not completely useless. You do, however, have to look at the raw data. The problem is that most tools that look at SMART blindly listen to what the manufacturers recommend. We, instead, take the approach that a reallocated sector count greater than zero means the drive is failing, and errors in the SMART logs are a bad sign. You'll need something like smartctl from smartmontools to view it all.